Lesson 1 Flashcards
(117 cards)
1
Q
What makes objects visible in a room?
A
Light that is reflected off objects and received by our eyes.
2
Q
What are some common phenomena associated with light?
A
- Image formation by mirrors
- Twinkling of stars
- Colors of a rainbow
- Bending of light by a medium
3
Q
What does the straight-line path of light indicate?
A
Light travels in straight lines, as demonstrated by sharp shadows of opaque objects.
4
Q
What is diffraction of light?
A
The bending of light around small opaque objects, indicating that light behaves as a wave.
5
Q
How did the understanding of light evolve in the 20th century?
A
The wave theory of light was found inadequate; modern quantum theory reconciles light’s particle and wave properties.
6
Q
What are the laws of reflection of light?
A
- The angle of incidence equals the angle of reflection
- The incident ray, normal, and reflected ray lie in the same plane
7
Q
What type of image is formed by a plane mirror?
A
Virtual, erect, same size as the object, and laterally inverted.
8
Q
What is a concave mirror?
A
A spherical mirror with a reflecting surface curved inwards.
9
Q
What is a convex mirror?
A
A spherical mirror with a reflecting surface curved outwards.
10
Q
What is the pole of a spherical mirror?
A
The point on the surface of the mirror, represented by the letter P.
11
Q
What is the centre of curvature of a spherical mirror?
A
The centre of the sphere of which the reflecting surface is a part, represented by C.
12
Q
What is the radius of curvature of a spherical mirror?
A
The radius of the sphere of which the reflecting surface forms a part, represented by R.
13
Q
What is the principal axis of a spherical mirror?
A
A straight line passing through the pole and the centre of curvature, normal to the mirror at its pole.
14
Q
What happens when sunlight is focused by a concave mirror?
A
It converges at a point, creating a bright spot that can ignite paper.
15
Q
What is the principal focus of a concave mirror?
A
The point where reflected rays converge on the principal axis, represented by F.
16
Q
What is the focal length of a spherical mirror?
A
The distance between the pole and the principal focus, represented by f.
17
Q
What is the aperture of a spherical mirror?
A
The diameter of the reflecting surface.
18
Q
What is the relationship between the radius of curvature R and focal length f of a spherical mirror?
A
R = 2f.
19
Q
What happens to the image formed by a concave mirror when the object is at infinity?
A
The image is highly diminished, real, and point-sized.
20
Q
What happens to the image formed by a concave mirror when the object is between the focus and the mirror?
A
The image is enlarged, virtual, and erect.
21
Q
What are the key characteristics of images formed by concave mirrors?
A
- Real or virtual
- Enlarged, diminished, or same size
- Their nature depends on the object’s position
22
Q
What is the significance of ray diagrams in image formation?
A
They help locate the image of an object using the paths of light rays after reflection.
23
Q
What happens to a ray parallel to the principal axis when it strikes a concave mirror?
A
It reflects through the principal focus.
24
Q
What happens to a ray passing through the principal focus when it strikes a concave mirror?
A
It reflects parallel to the principal axis.
25
What happens to a ray directed towards the centre of curvature when it strikes a concave mirror?
It is reflected back along the same path.
26
What is the result of a ray incident obliquely to the pole of a concave mirror?
It is reflected obliquely following the laws of reflection.
27
What happens to light rays when they fall on a mirror along the normal to the reflecting surface?
The light rays come back along the same path.
28
What is the angle relationship for incident and reflected rays at the point of incidence?
The angle of reflection equals the angle of incidence.
29
What are the uses of concave mirrors?
* Torches
* Search-lights
* Vehicle headlights
* Shaving mirrors
* Dentists' tools
* Solar furnaces
30
What type of image does a convex mirror produce when an object is at infinity?
At the focus F, highly diminished, virtual and erect.
31
What is the nature of the image formed by a convex mirror when the object is between infinity and the pole?
Diminished, virtual and erect.
32
Why do we prefer a convex mirror as a rear-view mirror in vehicles?
Because they provide an erect, though diminished, image and have a wider field of view.
33
What is the principal focus of a concave mirror?
[key learning term]
34
What is the focal length of a spherical mirror with a radius of curvature of 20 cm?
10 cm.
35
What is the New Cartesian Sign Convention for spherical mirrors?
* Object is placed to the left of the mirror
* Distances to the right of the origin are positive
* Distances above the principal axis are positive
* Distances below the principal axis are negative
36
What is the mirror formula?
1/f = 1/v + 1/u.
37
How is magnification (m) defined in terms of height?
m = h'/h.
38
What does a negative magnification value indicate?
The image is real.
39
What does a positive magnification value indicate?
The image is virtual.
40
If a convex mirror has a radius of curvature of 3.00 m, what is its focal length?
1.50 m.
41
What is the nature of the image formed by a concave mirror when an object is placed at a distance of 25.0 cm with a focal length of 15.0 cm?
Real and inverted.
42
What phenomenon occurs when light travels obliquely from one medium to another?
Refraction of light.
43
What happens to a pencil that is partly immersed in water?
It appears to be displaced at the interface.
44
What is the effect of placing a glass slab over printed matter?
The letters appear raised.
45
What is the relationship between the height of the image and the object for magnification?
m = h'/h.
46
In the New Cartesian Sign Convention, what direction are distances measured from the pole of the mirror?
To the right is positive; to the left is negative.
47
What happens to the visibility of a coin placed at the bottom of a bucket filled with water when viewed from above?
It appears raised due to refraction.
48
What does the line under a glass slab appear to be when viewed from the sides?
It appears bent at the edges.
49
What happens to a light line under a glass slab that is placed at an angle?
The line under the glass slab appears to be bent at the edges.
50
What is observed when a glass slab is placed such that it is normal to the line?
The part of the line under the glass slab does not appear bent.
51
When looking from the top of the glass slab, does the line beneath appear raised?
Yes, the part of the line beneath the slab appears to be raised.
52
What is refraction of light?
Refraction is due to a change in the speed of light as it enters from one transparent medium to another.
53
What are the laws of refraction of light?
* The incident ray, the refracted ray, and the normal to the interface of two transparent media at the point of incidence all lie in the same plane.
* The ratio of sine of angle of incidence to the sine of angle of refraction is constant.
54
What is Snell's law of refraction?
The ratio of sine of angle of incidence to the sine of angle of refraction is constant for a given pair of media.
55
What does the refractive index represent?
The refractive index represents the ratio of the speed of light in one medium to the speed of light in another medium.
56
What is the refractive index of water?
The refractive index of water is 1.33.
57
What is an absolute refractive index?
The absolute refractive index is the refractive index of a medium considered with respect to vacuum.
58
How is optical density defined in terms of refractive index?
A medium with a larger refractive index is optically denser than one with a lower refractive index.
59
What happens to the speed of light when it travels from a rarer medium to a denser medium?
The speed of light decreases and the ray bends towards the normal.
60
What happens to the speed of light when it travels from a denser medium to a rarer medium?
The speed of light increases and the ray bends away from the normal.
61
What is a lens?
A lens is a transparent material bound by two surfaces, of which one or both surfaces are spherical.
62
What is a convex lens?
A convex lens is thicker at the middle and converges light rays.
63
What is a concave lens?
A concave lens is thicker at the edges and diverges light rays.
64
What is the principal axis of a lens?
The principal axis is an imaginary straight line passing through the two centres of curvature of a lens.
65
What happens to parallel rays of light passing through a convex lens?
They converge to a point on the principal axis called the principal focus.
66
What happens to parallel rays of light passing through a concave lens?
They appear to diverge from a point on the principal axis called the principal focus.
67
What is the focal length of a lens?
The distance of the principal focus from the optical centre of a lens.
68
Fill in the blank: The refractive index of diamond is ______.
2.42
69
True or False: The refractive index is the same as mass density.
False
70
What is the meaning of a refractive index of 1.50 for glass?
It indicates that light travels 1.50 times slower in glass than in vacuum.
71
Which medium has the highest optical density according to Table 9.3?
Diamond with a refractive index of 2.42.
72
Which medium has the lowest optical density according to Table 9.3?
Air with a refractive index of 1.0003.
73
What is the effect of a convex lens on sunlight?
It converges the light to a point, which can generate heat and potentially burn paper.
74
What is the principal focus of a concave lens?
The point on the principal axis where rays diverge from the lens.
75
How many principal foci does a lens have?
Two principal foci, represented by F1 and F2.
76
What is the focal length of a lens represented by?
The letter f.
77
How can you find the focal length of a convex lens?
By measuring the distance between the lens and the image of the Sun.
78
What is the nature of the image formed by a convex lens when the object is at infinity?
Highly diminished, real, and inverted.
79
Fill in the blank: The nature, position, and relative size of the image formed by a convex lens can vary depending on the _______.
[position of the object].
80
What type of image does a concave lens always produce?
A virtual, erect, and diminished image.
81
What is the sign convention for the focal length of a convex lens?
Positive.
82
What is the lens formula?
1/f = 1/v + 1/u.
83
Define magnification in terms of a lens.
The ratio of the height of the image to the height of the object.
84
What is the SI unit of power of a lens?
Dioptre, denoted by the letter D.
85
What does a positive power of a lens indicate?
The lens is convex.
86
What is the power of a lens with a focal length of 1 meter?
1 dioptre.
87
How is the net power of lenses in contact calculated?
By the algebraic sum of the individual powers.
88
True or False: The focal length of a concave lens is positive.
False.
89
What happens to the size of the image when the object is moved further away from a concave lens?
The image size diminishes.
90
What is the relationship between object distance (u), image distance (v), and magnification (m)?
m = h'/h = v/u.
91
What is the nature of the image formed by a convex lens at 2F1?
Same size, real, and inverted.
92
What is the focal length of a concave lens with a power of -2.5 D?
-0.40 m.
93
What occurs to light rays passing through the optical center of a lens?
They emerge without any deviation.
94
Fill in the blank: The power of a lens is defined as the _______ of its focal length.
[reciprocal].
95
What happens when a light ray travels from a denser medium to a rarer medium?
It bends away from the normal.
96
What is the conclusion drawn from observing the image through a concave lens?
It will always be virtual, erect, and diminished.
97
What is the relationship between the focal length and radius of curvature of a spherical mirror?
The focal length of a spherical mirror is equal to half its radius of curvature.
98
How is magnification defined in the context of spherical mirrors?
Magnification is the ratio of the height of the image to the height of the object.
99
What occurs to a light ray when it travels from a denser medium to a rarer medium?
It bends away from the normal.
100
What is the speed of light in a vacuum?
3×10^8 m s^-1.
101
What does the refractive index of a transparent medium represent?
The ratio of the speed of light in vacuum to that in the medium.
102
In a rectangular glass slab, what happens at the air-glass interface?
Refraction takes place.
103
What is the lens formula for a spherical lens?
1/f = 1/v + 1/u.
104
What is the power of a lens?
The reciprocal of its focal length.
105
What is the SI unit of power of a lens?
Dioptre.
106
Fill in the blank: A __________ lens is used to read small letters found in a dictionary.
convex lens of focal length 5 cm.
107
What type of mirror is used in the headlights of a car?
Concave mirror.
108
What type of mirror is used in the side/rear-view mirror of a vehicle?
Convex mirror.
109
What type of mirror is used in a solar furnace?
Concave mirror.
110
True or False: A concave mirror can produce an erect image.
True.
111
If one-half of a convex lens is covered with black paper, will it produce a complete image?
Yes.
112
What does a magnification of +1 from a plane mirror indicate?
The image is of the same size as the object.
113
What is the focal length of a lens with a power of -2.0 D?
The focal length is -0.5 m.
114
Is a lens with a power of +1.5 D converging or diverging?
Converging.
115
What is the nature of the image formed by a concave mirror when the object is between the pole and principal focus?
Virtual and erect.
116
At what distance should a screen be placed to obtain a sharp focused image from a concave mirror?
The distance should be equal to the image distance calculated.
117
Where should an object be placed in front of a convex lens to get a real image of the size of the object?
At twice the focal length.
